I'm very glad to hear that you're pleased with OJS and are interested in helping out with other PKP projects. We'd be very happy for you to try out Lemon8-XML as an alpha tester so you can get a feel for it.
Just for reference, to date we have only been soliciting testers in a very limited fashion since the major features of L8X are not yet quite completed. However, we understand that many people are interested in simply having a look at how the application works, understanding that at the moment certain aspects (the document parser in particular) do not work particularly well (although improvements are already underway).
You can take the current testing version of L8X out for a test drive on our server to become more familiar with how it operates: http://www.lemon8.org/users/login/
The login is "lemon8" and the password is "xmldoc". This installation will be regularly purged of all data, so please do not use it for anything other than making a short-term evaluation of the software.
There have been a few changes in priority which have taken precedence over L8X, but we are still on track to have the major features completed for a move into public beta some time in the early spring. At that point, it will be open to anyone to create their own account, and we will be soliciting bug reports to help us polish the code so it can be released openly.
Hope this helps, and thanks again for your interest!